Container molding and trimming method and apparatus

ABSTRACT

A method and apparatus for molding plastic containers and the like, and for removing unwanted flash material therefrom. In the molding step, the unwanted dome portion of a container is molded to have a conveyor engaging groove therein, and the unwanted tail flash portion is molded to have a weakened line area at the point of attachment to the bottom of the container. After ejection from the mold, the container is conveyed to a tail removal device that grips and tears the tail along the weakened line area by a downward and rearward force. The container is conveyed to a dome removal device that engages the groove in the dome, moves the dome against a cutting edge, and rotates the container to effectuate a complete removal of the dome. The tail and dome removal operations are performed quickly and cleanly immediately after ejection of the containers from the mold while the plastic is still hot and pliable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for blow moldingplastic containers and the like and for removal of unwanted flashmaterial therefrom, and particularly to molding of the dome portion andthe tail portion of the containers to facilitate removal thereof.

2. Description of the Prior Art

In the process of molding bottles or other containers, the articles areformed from an extruded parison held between a pair of mating moldhalves. After forming of the article, the mold halves are separated andthe molded article ejected. It is common for flashings, which refers toa fin-like web projecting from the surface of the material, to be formedat the parting line across the bottom of the bottle or container wherethe mold halves are in engagement. It is also common for a ball-likedome to form at the top of the container above the neck. These flashingsmust then be removed in a separate operation, either by hand or byautomatic machines.

While there are many devices and apparatus for removing flashings, themost common approach is to utilize mating dies that grip around the neckof the container and at the bottom of the container. When such dies areused, the container must be rigid to be able to retain its shape underthe force of the dies. Immediately after molding of the container, theplastic material remains in a softened condition and therefore it isnecessary to cool the container before conventional trimming operationscan be accomplished. The storage, handling, and entering of containersin an automatic machine utilizing dies requires additional space andcosts. Such equipment is relatively expensive since the dies must bematched to the shape of the container in production.

Machines have been developed in the prior art for trimming bottles orcontainers while still hot but which have required specific jigs to holdan individual bottle during trimming. For example, in U.S. Pat. No.3,795,162 to Jaeger, a milk container is held by its neck and handlewhile a swinging arm cuts the tail flashing from the bottom of thebottle. Other apparatus for removing the tail flashing from a blowncontainer as taught in U.S. Pat. No. 3,677,454 to Boyer, uses a chainand bar mechanism positioned below the dies of the blow molding machineswhich grasps the tail portion and moves the article up an inclined planein a direction away from the moving chain. In effect, the tail surfaceis held and the container forced upward with a tearing motion. In thisapproach, the container must move through several planes, and changes ofdirection of motion are required resulting in a complex and expensiveequipment. Apparatus for removing flashing such as a dome from the neckof a molded container includes that described in U.S. Pat. No. 3,429,211to Pelot, which requires a fixed guide and a movable guide gripping thehollow neck while moving the unwanted portion against an adjustablecutting tool obliquely disposed along the direction of travel of thecontainers. Thus, a special neck design of the bottle is required toutilize this apparatus since a specific type of groove in the neck ofthe container must be provided to match the fixed and movable guides.

SUMMARY OF THE INVENTION

The apparatus of the present invention provides a mold with specialshaping of the dome portion and the tail portion of the container; aconveyor for moving containers from the mold to a tail removing element,and for further transport to a dome removing element.

The containers in accordance with the invention have a round neck andmouth section. In the mold, the waste portion above the neck and mouthsection is formed to provide a deep groove around its periphery. Thetail portion is molded to have a pinched in or weakened area along aline where the tail is attached to the bottom of the container. Each endof the weakened line area is notched.

A group of containers is ejected from the mold via a guiding device ontoa moving drive rope type of conveyor such that the tail is aligned withthe direction of travel of the drive rope. The containers are then movedinto a device which grips the tail as the containers are moving alongthe line of the guide. The gripping device is arranged to also apply agradually increasing downward pull on the tail effectively tearing thesoft web free from the bottom of the container starting at the notch andcontinuing through the weakened line area. The waste tail is collectedfor re-use. As the containers move from the tail removing device, theyare guided into the dome removal section of the apparatus. Thecontainers leave the conveyor and are caught by a moving endless ropedrive arranged to engage the dome section of the container and to urgeone side thereof against a sharp stationary cutting edge aligned withthe rope drive. The moving rope causes the entire container to rotateagainst the stationary blade, cleanly cutting the dome section free fromthe container. After the dome is completely separated from thecontainer, it is collected for subsequent re-use of its material. Atthis point, the trimmed containers are discharged from the apparatus forpacking or other operations.

The tail flash removing device consists of a novel gripping and tearingelement comprised of two tapered elongated rollers disposed in ahorizontally opposed fashion with the tapers causing a slight anglebetween the two rollers, forming a V with the open end of the V towardthe incoming containers to be trimmed. The container guide and conveyorincludes a slotted base portion through which the tail flash extends,allowing the bottom of the container to rest on the guide surface, withthe tail portions of each container longitudinally aligned in thedirection of movement. While various positive means are available formoving the containers, a novel rope drive technique is utilized whichprovides movement of the containers without damage to the still softplastic. A pair of parallel endless rope-like belts formed from anelastomeric material is disposed along the direction of desired travelof the containers and in contact with opposite sides of each container.Due to the friction between the elastomeric rope and the sides of theplastic container, the movement of the rope carries the containers alongthe desired path.

The conveyor thus moves the tail portion of each container into the openend of the V formed between the two rollers. Each roller is knurled andserrated with the serrations forming an angle with the axis of therollers. The rollers are rotated inwardly and downwardly at a peripheralvelocity about twice the velocity of the conveyor such that the opposingfaces of the rollers are rotating downward. As the tail flash of acontainer is carried in between the rollers, it will move freely untilthe space between the rollers becomes approximately equal to thethickness of the tail flash. At this point, the serrations first gripthe soft tail flash and, due to the downward rotation of the two rollerfaces, a downward pull or tearing motion is applied to the leading edgeof the tail flash. Simultaneously, the container is being moved furtherinto the V space between the rollers by the conveyor. The downward pulland forward motion result in a diagonal force vector which tends to tearthe tail along the weakened line at the mold seam on the bottom of thecontainer. As may be seen, the first downward pull is applied to justthe leading edge of the tail flash; however, as the container continuesto move, more and more of the surface of the tail flash is gripped bythe counter-rotating rollers with the downward force thereby increasingas a larger portion is gripped. The gripping action can be understood totherefore continue to tear away the flash as the container progressesuntil the point is reached at which the tail flash is completelyseparated from the bottom of the container. The area of the rollers overwhich this operation will occur with respect to the rollers isdetermined by the thickness of the web forming the tail flash which mayvary slightly from container to container. Therefore, the taperedrollers advantageously will accommodate various thicknesses. Theseparated section of plastic forming the tail flash may be collected bya vacuum system and returned for recycling of the plastic.

As the container leaves the tail removal section and enters the domecutting portion of the apparatus, the container must be free to rotateabout an approximate center axis. Where rectangular or square bottlesare being trimmed, the guides and drive rope would interfere with therotation. Consequently, the container is transferred from the primaryrope drive to a secondary rope drive having a more positive action andspace for the required rotation. The rope is formed from an elastomericmaterial having a high coefficient of friction with respect to thebottle material. The belt engages the groove molded into the domesection on one side and forces the opposite side tightly against aserrated guide rod on the opposite side. The motion of the belt is torotate the container by its dome section as the container is movedforward, causing the cutter edge to completely separate the dome afterone complete revolution. The serrated rod prevents slipping as thecontainer is rotated.

After rotation of the container and removal of the dome, the trimmedcontainers leave the rotational drive and are carried from the dometrimming section to the primary rope drive.

It is necessary for square or rectangular bottles or containers to beable to rotate in the cutter portion of the apparatus withoutinterference with each other. Therefore, a selected space betweensuccessive containers in the line must be provided. To this end, aspacing guide is provided at the entry to the dome removal system of theapparatus.

As may be noted, the apparatus in accordance with the invention providesa simple inexpensive apparatus which quickly and easily removes the tailflash and dome flash from blow molded plastic containers while still hotfrom the mold quickly and cleanly and collects the waste material forre-use. The containers remain hot from the mold and relatively soft forease of trimming for approximately three minutes. Advantageously, thetransit time through a trimming apparatus in accordance with theinvention may be on the order of 1/2 minutes and before cooling occurs.The pre-molding of the waste portions of the containers is used toadvantage in removing the tail portions quickly and cleanly withoutdamage to the containers, and in rotating the dome portion against acutter for positive trimming.

It is therefore a principal object of the invention to provide a methodand apparatus for molding plastic containers and similar articles inwhich the waste flash portions thereof are specially formed tofacilitate removal from the article after ejection from the mold.

It is another object of the invention to provide apparatus that willsequentially mold a plastic container, eject the container from themold, remove the tail flash portion, and remove the neck flash portion.

It is another object of the invention to provide improved apparatus forremoving the tail flash from freshly molded plastic containers utilizinga novel counter-rotating knurled roller assembly for gripping andtearing of the tails from the bottom of the plastic containers withoutdamage thereto while the containers are in motion.

It is still another object of the invention to provide an apparatus forengaging a special groove molded into the waste portion above the neckarea of a plastic molded container to thereby rotate the container.

It is a further object of the invention to provide apparatus having aknife edge against which the neck areas of the plastic molded containersare rotated for removing of the upper waste area.

It is still a further object of the invention to provide a blow moldapparatus which will mold a groove around the peripheral of the wasteplastic above the neck area of a plastic molded container.

It is another object of the invention to provide apparatus for blowmolding of a plastic container having a tail flash area in which thetail portion is molded to have a pinched-in or weakened area along theline where the tail is attached to the bottom of the container.

It is another object of the invention to provide apparatus for molding aplastic container having a tail flash area in which a weakened line areaalong the tail portion includes a notch to facilitate starting of a tearduring subsequent separation of the tail portion from the container.

These and other features and objects will be most readily understoodfrom the following detailed description of the invention with referenceto the included drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a pair of split-mold halves showingthe cavities therein for blow-molding of a square-bodied plasticcontainer suitable for juices and the like;

FIG. 2 is a partial view of the face of one half of the mold section ofFIG. 1 illustrating the form of the tail flash portion of the mold;

FIG. 3 is a greatly simplified and partial side view of the moldingsection of the invention showing the ejection of molded containers ontoa conveyor system;

FIG. 4 is a cross-section 4--4 of FIG. 3 showing the position of amolded container on the conveyor system;

FIG. 5 is a greatly simplified and partial side view of a section of theinvention utilized to remove the tail flash portion from the moldedcontainers;

FIG. 6 is a top view of the tail removal section of FIG. 4 in greatlysimplified and partially cut-away form to show certain details thereof;

FIG. 7 is a cross-sectional view of FIG. 5 at plane 7--7 showing in moredetail the secondary rope drive system and the counter-rotating rollers;

FIG. 8 is a greatly simplified side view of the dome removal section ofthe invention;

FIG. 9 is a greatly simplified top view of the dome removal section ofthe invention showing additional details thereof; and

FIG. 10 shows a partial cross-section of a container moving through thedome removal section of FIGS. 8 and 9, showing in greater detail thesecondary drive and rotational system of the invention, and the cutterfor removing the dome flash portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is to be described hereinafter as applying to amethod and apparatus for producing bottles, containers, or other likearticles manufactured from heat deformable plastic material that isextruded into a parison, injected into a mold, and shaped by a blowmethod or the like to a desired final configuration within the mold.

An element of the present invention is a special formation of the wasteor "flash" portions of the final molded article. While any number ofdifferent types of containers may be manufactured utilizing the methodof this invention, a preferred embodiment will be described withreference to a small square bottle having a rounded neck and mouththereof, such as may be made in a six ounce size for containing fruitjuices and the like. Referring to FIG. 1, a partial cross section of aset of split mold cavity blocks is shown by numerals 10 and 11. This setof mold cavity blocks is used in conjunction with a typical blow moldmachine which is well known to those skilled in the art and thereforeonly a portion of the cavity blocks having a single bottle mold 9 isillustrated in the drawing with the special design of the flash or wasteportions shown. The main body of the bottle is indicated by cavity 12with the desired cavity for forming the neck and sealing portion of thebottle shown at 16. Portions of the mold above the neck rim and lip 16are indicated by the numeral 15 and represent waste portions thereof.Waste portion cavity below the bottle 12 is shown by the numerals 13, 14and 17. The portion of the bottle above the neck lip 16 is known as a"dome" formed by mold part 15. As seen in FIG. 3, the dome portion of afinished bottle 20 is identified by numeral 23. Of particular note isthe circular groove 22 as seen in FIG. 3 produced in the blown bottle bythe mold portion 15' as will be discussed in detail hereinbelow.

When the parison is blown, the waste portion at the bottom of the moldextrudes into cavity 14 between the mold pair 10 and 11 forming a "tail"flash. As seen in FIG. 2, which is a face view of mold half 10, tailcavity 14 is seen to have a keystone shape. This tail flash 25 formed onthe finished bottle 20, as well as the dome flash 23, must be removedfrom the blown bottle after removal from mold 10 and 11. Tail 25 has aline of reduced cross-sectional area produced by mold part 13 along thebottom of bottle 20 as best seen in FIG. 1. Advantageously, this sectionwhich is produced by mold part 13, is much weaker than the main portionof the tail produced in cavity 14. The edges of tail portion 25 areproduced by the relief area 17 in the mold sections 10 and 11. Tail 25also has a pair of notches produced by mold section 13 at either end ofthe weakened line and indicated in FIG. 2 by the numeral 16.

A skeletal side view of the apparatus in accordance with the inventionmay be seen by a combination of FIGS. 3, 5 and 8 in which the supportingstructure and drive systems are omitted for clarity. Such ancillaryportions of the apparatus are conventional and any well-known methodsand structures may be used for such purpose. The apparatus comprisesthree main sections: the blow-molding section shown generally as numeral18 in FIG. 3; the tail removing section generally shown by numeral 40 inFIG. 5; and the dome removal section shown generally by numeral 70 inFIG. 8.

Turning now to FIG. 3 and FIG. 4, details of the mold section 18 will bedescribed. A split mold cavity block is indicated by numeral 5 which inthis exemplary illustration contains mold cavities for five bottles,although, of course, any number may be utilized. The mold cavity 9 isindicated for example in FIG. 3 by dashed lines. Directly below moldblock 5 is bottle guide 6. As mold block 5 is opened after blowing of aset of bottles, the bottles are allowed to drop in the direction ofarrow A with guide passage 7 shown in partial cut-away view in bottleguide 6 causing bottle 20 to drop straight down with its flat sidesbeing guided through passage 7 so as to enter a primary conveyor system,shown generally at numeral 29, with tail 25 aligned longitudinally withthe direction of motion of conveyor system 29. Conveyor system 29utilizes a drive rope fabricated from an elastomeric material, with asuitable rope for this purpose being available from the Eagle Company.The rope material is flexible and has a high coefficient of frictionalong its surface. Idler pulleys 33 are spaced at appropriate intervalsalong drive rope 30 to provide sufficient support. Side guides 32 aredisposed along the line of movement of conveyor rope 30 and spaced asbest seen in FIG. 4 to accept the sides of bottle 20. Conveyor rope 30is displaced slightly from a center line as shown so that tail 25 maydrop from the mold free of rope 30. The friction between drive rope 30and the bottom of bottle 20 as well as with the side of tail 25 causesthe rope to move the bottles in the direction shown away from the moldarea. As may be understood, the process of molding, dropping of thebottles, and the conveying of the bottles away is a continuous cycle inproduction.

Turning now to FIG. 5, the tail removal section 40 of the apparatus inaccordance with the invention shall be seen. As indicated by the letterX, the apparatus of FIG. 5 is a continuation of and connected directlyto the mold section 18 of FIG. 3. Generally, an appropriate length ofconveyor 29 will be provided between sections 18 of FIG. 3 and section40 of FIG. 5 to allow an inspector to observe the flow of bottles and tocorrect any misalignment or to remove defective bottles. The tailremoval section 40 of FIG. 5 utilizes a pair of slightly taperedserrated rollers 44 and 45 as seen in FIG. 5 and FIG. 6. FIG. 6 is a topview of section 40 of the invention with certain parts partially cutaway to more clearly reveal the construction thereof. As may be noted,rollers 44 and 45 are disposed with the axes thereof parallel to thedirection of travel of the bottles with the small ends of the tapers atthe incoming end of section 40 and the large ends touching at the outputend of section 40. Rollers 44 and 45 are serrated with knurling typecuts at an angle with the axis of the rollers. The rollers 44, 45 arecounter-rotating in an inward and downward direction as indicated byarrows B and C. As the bottle 20 arrives at the tail removal section 40,the tail 25 is aligned horizontally in the direction of movement. It isnext required to move bottle 20 through tail removing section 40positively and, to this end, a separate drive system utilizing drives 49and 51 is provided. The drives 51 and 49 consist of a drive ropearrangement with parallel drops ropes 50 and 60 on either side of theconveyor such that the sides of bottle 20 are firmly gripped between thetwo ropes 50 and 60 which cooperate to move the bottles in the desireddirection of travel. To provide space for rollers 44 and 45 below thebottles, the tail removal section 40 is displaced slightly from the lineof primary drive rope 30 as indicated best in the top view of FIG. 6.Two auxiliary guides 41 and 42 formed from round bar stock are disposedso as to catch bottle 20 just below rim 24 with the spacing betweenguides 41 and 42 forming a snug fit with the bottle at this point. Thepositioning of guides 41 and 42 are best seen in FIGS. 5 and 7. A guideplate 48 is utilized as a support for the bottles and to maintain tail25 in horizontal alignment by means of slot 49 as the bottles leave theprimary conveyor rope 30 and proceed into tail removal section 40. As abottle moves into position as shown by bottle 20a in FIG. 5, it may benoted that tail 25a will move between the small ends of rollers 44 and45. As shown in FIG. 5, bottle 20b has moved to the point where theleading edge of tail 25b is contacted by counter-rotating rollers 44 and45. As the serrations thereon grip the soft plastic of tail 25b, adownward directed force shown by arrow D will be applied over a narrowstrip along the leading edge. This downward force combines with thetranslational force due to the movement of the bottle by conveyorelements 51 and 49 to produce a force vector downward and rearwardtending to tear the leading edge of tail 25b from the bottom of bottle20b. In accordance with the invention, the notch at 16 (see FIG. 2) andthe reduced cross-section due to section 13 of the mold (see FIG. 1 andFIG. 2) will result in a tear beginning at this point. Bottle 20c,having moved further into the tapered rollers 44 and 45, experiences thedownward and rearward force over a larger area of tail 25c resulting ina force vector E at a more acute rearward angle continuing the tearingaction of the reduced thickness web of tail 25c. This process, ofcourse, continues and as shown for bottle 20d has resulted in almosttotally separation of tail 25d from the body of bottle 20d. Bottle 20ehas progressed along rollers 44 and 45 to the point where its tail 25ehas been completely removed. The tail 25e and an earlier removed tailare shown dropping in the direction F to a waste recovery system. Thewaste recovery system (not shown) utilizes a small hopper and vacuumsystem which catches the waste plastic and sends it back for recycling.The remainder of the bottles shown in FIG. 5 having the tail portionsremoved are carried by secondary conveyors 51 and 49 via guides 41 and42 back into guides 32 and onto primary conveyor rope 30 for furtherprocessing.

The advantageous result of the novel design of molds 10 and 11 toproduce the narrow web by mold portion 13 and the notches 16 results ina clean, smooth removal of the tail 25 from bottle 20 with no damage tothe bottom of the bottle. As may be noted most clearly in FIG. 7, thetail guide 45 firmly supports the base of bottle 20b as the tail portionis being torn free, thus preventing distortion or damage to the bottomof bottle 20b. It is pertinent to note that placing the tail removalsection 40 immediately after the ejection of the bottles from mold 9onto primary conveyor 29 results in the plastic remaining relatively hotand pliable; therefore, the tearing action just described is easily andcleanly accomplished.

Next, the output from tail removal section 14 at Y of FIGS. 5 and 6connect to the input Y of dome removal section 70 shown in FIGS. 8 and9. Dome removal section 70 utilizes a secondary drive system showngenerally by 71 comprising drive rope 72, drive pulleys 76, and serratedguide 74. A horizontal cutter 80, having a cutting edge aligned with thedirection of travel of the bottles is utilized for cleanly removing domesection 23 from the bottles. Secondary conveyor 71 is provided to movethe bottle positively in the direction of travel and simultaneously torotate the bottle against the cutter 80 to effect the desired removal ofthe dome section 23. As a bottle 20f in FIG. 8 is carried into the domeremoval section 70, it encounters a spring-loaded section 83 of guide32. The purpose of this guide section 83 is to slow the forward movementof bottle 20f slightly to allow the previously released bottle 20g tomove adhead slightly with a space between the two successive bottles sothat each bottle can freely rotate without mutual interference.

The action of secondary conveyor 71 is best understood from a partialcross-sectional view of bottle 20g shown in FIG. 10. Drive rope 72 movesin a groove in a guide block 78 constructed of a material such as Teflonor Nylon in which it may slide freely yet be firmly supported againstgroove 22g advantageously formed in waste portion 23g of bottle 20g bymold portion 15' of FIG. 1. Serrated bar 74, shown in cross-section, isheld firmly against groove 22g directly opposite from drive rope 72. Thespacing between serrated bar 74 and drive rope 72 is such that dome 23gis squeezed in slightly at groove 22g with the natural resilience of theplastic material thereby providing a firm purchase between both thedrive rope 72 and bar 74. The serrations on bar 74 bite slightly intothe soft plastic and thereby prevent slippage of the bottle 20g as it isthen rotated by the forward movement of drive rope 72. This rotation isindicated at H in FIG. 9. As bottle 20g encounters the forward edge ofcutter 80, the cutter cuts through the plastic at the top lip of rim 24gjust below dome section 23g. As the bottle is rotated and moved along inthe direction of travel, the blade 80 then cleanly cuts the plasticuntil 360 degrees of rotation has occurred at which time the domesection 23g will be free from the main part of bottle 20g. At this pointthe bottle is released from secondary drive 71 and, as shown by bottle20h, is caught by primary conveyor rope 30 and carried out of the domeremoval section 70. The cut away dome 23g is carried by secondaryconveyor 71 and as discharged is caught by a vacuum from scavenger tube82 and carried to the waste recycling system. The completely finishedand trimmed bottles as at 20h are then delivered by the main conveyorsystem 29 for final inspection, packing, labeling, or other processing.

The rate at which bottles or other containers can be formed and trimmedin accordance with the invention is a function of the basic blow moldmachine design. The tail removal and dome removal portions of theinvention can operate at relatively high speeds and will not limit theoutput. For example, each operation requires only a few seconds, and inone embodiment of the invention the time from beginning of molding tothe completely trimmed bottle has been found to be less than 30 seconds.A typical bottle may require on the order of three minutes to cool toits final state, therefore, this short time permits the bottle to remainsoft and plastic during the above-described operations.

As may be recognized from the operational description of the apparatusin accordance with the present invention, the process may be seen to beone of molding the waste or flash portions of a container or similarblown article in a manner to simplify and assist in removal of suchflash portions. The method contemplates specifically: molding a turninggroove in the dome portion of the article; molding a weakened portionwhere the tail connects to the article; ejecting the article from themold; moving the article into a gripping and tearing device; creating aforce vector tending to start a tearing action at the weakened line areaof the tail at its leading edge; carrying the article forward to therebycleanly tear the tail free from the article; gripping the groove in thedome waste portion of the article securely by a conveying and rotatingdevice; and moving the article along a sharpened cutting edge disposedat the parting line between the waste dome and the article, such thatthe article rotates as it moves along the cutting edge thereby cleanlycutting the waste dome free from the article.

It is also important to note that the trimming operations in accordancewith the present invention permits full output of a blow molding machineto be maintained without delay incurred for such trimming operation.Therefore, savings in operational time and production rates are obtainedover prior art methods.

While the preferred embodiment of the invention has been shown withrespect to a specific type of bottle and a specific arrangement of theelements thereof, it is clear that many modifications and changes indetails may be made by those of ordinary skill in the art withoutdeparting from the spirit and scope of the invention.

I claim:
 1. A method for trimming an unwanted portion from moldedplastic containers, said method comprising:conveying said containersalong a first direction; providing a cutting means having a cutting edgetraversing said first direction; positioning said cutting means toengage and cut said unwanted portion from said containers while saidcontainers are conveyed along said first direction; engaging saidunwanted portion before and during said engagement with said cuttingmeans to rotate each of said containers and the corresponding unwantedportion to effectuate a complete removal of the unwanted portion by saidcutting means.
 2. The method as defined in claim 1 in which saidunwanted portion has a peripheral groove therein.
 3. The method asdefined in claim 2 wherein said engaging step comprises engaging saidgroove with an endless rope of elastomeric material, said endless ropehaving a straight section thereof moving along said first direction,said straight section engaging said peripheral groove of said unwantedportion.
 4. The method as defined in claim 3 further comprising astraight length of rod having serrations on the face thereof, said roddisposed diametrically opposite and parallel to said straight sectionand engaging the opposite side of said peripheral groove, said straightsection and said rod being spaced and securely gripping said unwantedportion in said peripheral groove wherein movement of said endless roperotates the molded plastic containers.
 5. The method as defined in claim4 further comprising pneumatically collecting said cut, unwanted portionimmediately following complete removal thereof.
 6. A system for trimmingunwanted peripheral material from plastic containers, comprising:pluralplastic containers having unwanted peripheral material and a groove insaid unwanted material; a flexible conveyor having a cross-sectionalshape conforming to the shape of said groove in said unwanted peripheralmaterial and engaging said material in said groove, said conveyor movingsaid containers along a first direction; a rod having a cross-sectionalshape conforming to, and engaging said material in said groove, said rodbeing disposed diametrically opposite and aligned with said flexibleconveyor, said rod serving to guide said plastic containers in saidfirst direction; cutting means having a cutting edge traversing saidfirst direction and positioned to engage and cut said unwantedperipheral material from said container, said conveyor moving saidcontainer in said first direction parallel to said cutting edge tosimultaneously move said container along and against said cutting edgeand rotate said container on its axis to present the entire periphery ofsaid unwanted material to said cutting edge to effectuate a completeremoval thereof.
 7. A system as defined in claim 6 in which saidflexible conveyor comprises an endless rope of an elastomeric material.8. A system as defined in claim 7 in which said rod is serrated along aface presented to said groove.
 9. A system for removing unwantedportions from plastic containers, comprising:plural plastic containers,each having an upper unwanted portion and a peripheral groove aroundsaid upper unwanted portion; a conveyor having a moving element with across-sectional shape conforming to the shape of said peripheral grooveand engaging said upper portion of each container in said peripheralgroove, said conveyor utilizing said moving element for moving saidcontainers along a first direction; a rod having a cross-sectional shapeconforming to the shape of, and engaging said upper portion in saidperipheral groove, said rod being disposed diametrically opposite andaligned with said moving element for moving said plastic containers insaid first direction; cutting means having a cutting edge traversingsaid first direction and positioned to engage and cut said unwantedupper portion from said containers, said conveyor moving said containersin said first direction transverse to said cutting edge tosimultaneously move said containers through said cutting edge and rotateeach said container on its axis to present the entire periphery of saidunwanted upper portion to said cutting edge to effectuate a completeremoval thereof.
 10. A system for trimming unwanted tail flash portionsand dome portions from molded plastic containers immediately aftermolding thereof, comprising:plural plastic containers having unwantedtail flash and dome portions; first conveying means for accepting saidcontainer immediately after molding thereof and for moving saidcontainers in a first direction; guide means for guiding said containersin said first direction; rotary gripping and tearing means adapted togrip the tail flash portion of each of said containers consecutively assaid containers move in said guide means and to provide a generallydownward and rearward tearing force on said tail flash portion andadapted to completely separate said tail flash portions from saidcontainers; cutting means having a cutting edge parallel to said firstdirection and said guide means and positioned to engage and cut saiddome portion from said containers; and engaging and rotating means forengaging said dome portions to rotate each of said containers at least360°, said engaging means forcing said dome portions against saidcutting edge whereby such rotation effectuates a complete removal ofsaid dome portions.
 11. Apparatus for producing molded plastic bottlescomprising:plural plastic bottles, each having a groove in a waste domeportion thereof attached to the neck of said bottle, and a waste tailportion having a weakened area therein; conveyor means for accepting andmoving said bottles along a first direction; rotary and tearing meansadapted to grip the tail portion of each of said bottles consecutivelyas said bottles moving along said first direction to provide a generallydownward and rearward tearing force on said weakened area of said tailportion for completely separating said tail portion from said bottles;cutting means having a cutting edge parallel to said first direction andpositioned to engage and cut said waste portion from said neck; andengaging means for engaging said groove in said waste dome portion torotate each of said containers at least 360°, said engaging meansforcing said waste dome portion against said cutting edge whereby suchrotation effectuates the complete removal of said waste portion.
 12. Amethod for producing a molded plastic container having a round neck, andfor removing an unwanted dome portion connected to the neck of saidcontainer and an unwanted tail portion connected to the bottom of saidcontainer, comprising the steps of:molding a plastic container in a moldto produce a groove in the unwanted dome portion attached to the neck ofthe container and a weakened line area in the unwanted tail portionconnected to the bottom of the container; removing the container fromthe mold; moving the container along a first direction; gripping thetail portion progressively as the container moves along the firstdirection; tearing the tail portion free from the container along theweakened line area as the container moves along the first direction;engaging the groove in the unwanted dome portion by a means of rotation;rotating the container against a cutter edge at a line between the domeportion and the neck of the container; and cutting the dome portion freefrom the container.